1. Field of the Invention
The present invention relates to a spindle motor, and more particularly to a spindle motor in which a labyrinth seal is integrally formed with a spindle hub to prevent lubricant particles used in a bearing from being dispersed toward a neighboring clean area.
2. Description of the Prior Art
Generally, a spindle motor used in a magnetic recorder/reproducer such as a hard disk drive (HDD) and the like, has a pair of bearings b as shown in FIG. 1. Each bearing b is disposed in upper and lower portions of a shaft a and contains lubricant, for example, grease. When the bearings b containing the lubricant are rotated at a high speed, the lubricant is dispersed as fine particles or liquid-drops. If the lubricant particles are transferred to a clean area c and deposited on a disk d, an error can be caused upon a reading/writing operation on the disk d, and the life time of the disk d becomes shortened. Accordingly, respective bearings b are provided with a sealing member for preventing the dispersed lubricant particles from flowing into the clean area c. As the sealing member, a labyrinth seal s1 as shown in FIG. 1 or a magnet fluid seal s2 as shown in FIG. 2 is predominantly used. While the magnet fluid seal s2 provides an excellent sealing effect, it suffers from drawbacks in that when the spindle motor is rotated at a speed exceeding a predetermined speed, fluid magnet is apt to be dispersed to seperate from the bearings b. Also, since the magnet fluid seal s2 is separately manufactured from the spindle hub, the number of parts needed to construct the magnet fluid seal s2 is increased, manufacturing cost becomes high, assembling operations are required, and productivity is deteriorated.
Moreover, while the labyrinth seal s1 is inexpensive when compared to the magnet fluid seal s2, it still suffers from drawbacks in that since it is also separately manufactured from the spindle hub, assembling operations are required when the labyrinth seal s1 is interference-fitted on the spindle hub, and thereby productivity is also deteriorated.
Another labyrinth seal is disclosed in the Japanese Patent Laid-Open Gazette No. 7-286619. In the labyrinth seal disclosed in the Japanese Patent Gazette, a spindle motor which has a compact size and includes a magnetic fluid seal is is provided. However, since the magnetic fluid seal and a projection formed in a rotor hub are simultaneously provided to ensure the performance of the magnetic fluid seal, the number of parts needed to construct the labyrinth seal is increased, and substantial construction and assembling operations are required which reduces productivity.